PI3-kinase and the control of T cell growth and proliferation by FoxOs.

Numerous cancers are caused by an uncontrolled uncontrolled activity of the PI3-kinase pathway. The proto-oncogene Akt, one of its main effectors, commands several molecular switches involved in cell survival and proliferation. One of these switches is represented by a group of related molecules belonging to the Forkhead family of transcription factors, called FoxOs. FoxOs negatively control cell cycle entry and this process emerges now as a mainstream mechanism used by various cell types to escape cell quiescence. In the light of recent works, FoxOs seem also to have a key role in the proliferative response of immune cells, especially in the clonal expansion of T lymphocytes induced by antigen. Experimental evidence supporting a relationship in T cells between PI3-kinase metabolism and these growth suppressive genes will be described in this mini-review.